Communication system



wl s. LEMMON ET AL COMMUNICATION SYSTEM Filed Feb. l0, 1954 Patented May7, 1935 UNITED STATES PATENT OFFICE Y COMMUNICATION SYSTEM Walter S.Lemmon, New York, N.

Y., yand oxyde J. Fitch, Jersey City, N. J., assignors to InternationalBusiness Machines Corp., New York,

16 Claims.

The present invention pertains to a novel communication system designedfor the sending of messages by electrical impulses and is applicable toradio, carrier current and line transmission, etc. V

The invention embodies the use of synchronized disks or distributors atthe transmitting and receiving stations for completingthe transmittingand receiving circuits respectively similar to the synchronizing systemdisclosed in the co-pending application Serial No. 684,362 filed August9, 1933. At the sending station, the impulse is not transmitted untilcontact of reof the distributor corresponding to the actuated key forthe character to be sent; and at the instant of contact, the impulse issent out and caused to register the same character at the receivingstation, due to the synchronism of the contact disks or distributors.

In the present invention the characters are transmitted by thedepressionof key bars.

receiving mechanism.

The principal object of the invention is to matic View of the apparatus.Inasmuch as the receiving apparatus and sending apparatus are alike, adetailed description of only one of them Will suice.

The transmitting apparatus, (and also the receiving apparatus) includesa conventional or modified typewriter having a series of lettered andnumbered pivoted key bars I. Over the bars is mounted a roll 2 held in aslidable carriage (not shown) in the usual'manner so that it is movedone space on depression of any key bar. Each key bar has associatedtherewith a type bar 3 adapted to strike against the roll 2 ondepression of the corresponding key bar. This action is effected througha suitable linkage 4 between each key bar and its corresponding typebar. A sending distributor 5 carries a series of spaced contacts 6corresponding respectively to the various characters on the type bars I.The contacts are engaged in rather rapid succession by a rotary contactarm 1 driven by a chronism with the similar device at the other end ofthe transmission circuit and which is fully described in the co-pendingapplication stated hereinbefore.

Each 'of the key branch condenser circuit; from a contact 9 disposedrespectively beneath the `key bars, and normally spaced from the latterwhen the bars are in their normal or raised position, a line I0 isextended separately from each lower contact to individual condensers II,said condensers in turn connected to a corresponding key bar, so thatupon depressing the key bar, its corresponding condenser if chargedpreviously is discharged. Each of the key bars is comprised in a.circuit embodying common conductors I2 and I3 extending to rotary arml, in 'which are comprised a sending switch I4 closed 'at the sendingend, resistor I5, and condenser charging battery I6. 'Ihe correspondingswitch is open at the receiving end, as will be more fully describedhereinafter. From the distributor contacts 6 conductors I 1 extendseparately to xed contacts I8 positioned over the key bars. The lattercontacts are engaged by the corresponding bars I when the latter are inraised or released position and at such time close a correspondingcondenser charging circuit consisting of said bar I and contact I8,contact 6, rotary arm 1, conductor I3, battery I6, resistor I5, switchI4, conductor I2 and corresponding condenser II. Thus when any of thebars I is depressed, the corresponding condenser II will be shortcirmotor 8, which is in synbars I is comprised in a4 cuited anddischarged through the bar engaging contact 9 and conductor I6. Asending circuit is connected to the terminals of resistor I5 andcomprises the usual transmitting means.

The transmitter 20 as shown has one of its output terminals connected toan antenna 2I and its other output terminal 22 grounded in the usualmanner. As mentioned previously this invention is applicable to radio,carrier current and line transmission, for this purpose a transmissionline 2Ia is shown connecting the stations.

In the operation of the device as thus far described, it will be seenthat the depression of a key bar I rst breaks its condenser chargingcircuit to short circuit and discharge the condenser II. On the returnof the bar it engages its corresponding upper contact I8 and when therotaryA arm engages its contact 6 corresponding to the depressed keybar, the condenser charging circuit is completed, so that the dropacross resistor I5 caused by charging current pulse activates theconnected sending circuit I9 and transmitting apparatus 26, as a resultof Winch an impulse is transmitted.

In order to insure correct operation 'of the transmitting system uponstarting', the normally closed switch 40 included in the input circuitto the radio or line transmitter is opened until the individualcondensers II, which may have been discharged by leakage, are fullycharged by having all the distributor contacts 6 engaged successively bythe rotary arm 1 in a manner described above, and in this manner preventoperation of the receiving system which will now be explained.

The receiving circuit of each apparatus includes a receiver 23 havingone of its input terminals grounded at 24 and its other 4input terminalconnected to an antenna 25 or line 2Ia to receive the impulse sent outfrom transmitter 20 in the usual manner.

Beneath each of the key bars I is a solenoid 26 adapted to operate on aplunger 21 depending from the bar, so that when a given solenoid isenergized by the means presently to be described, the corresponding keybar will be depressed to actuate the corresponding type lever 3. Thereceiving circuit is governed by a receiving distributor 28 carryingelongated spaced contacts 29 corresponding in number and position tocontacts 6 on sending distributor 5.

The contacts 29 are of greater length circumferentially than contacts 6so as to hold the receiving circuit closed for an interval suicient toenable energization of the solenoids 26 and operation of the type bars 3as well as to allow for slight inaccuracies in the synchronism of therotary arms 1 and' 3D respectively. The rotary arm 3D wipes over thecontacts 29 and is driven by a motor 3l and rotates in synchronism withrotary arm 1 as previously disclosed, so that the arms of bothdistributors are in engagement'with similarly identified contacts at anyinstant.

The contacts 29 are connected separately to its corresponding solenoid26 by lines 32. A common conductor 33 extends from one of the outputterminals of receiver23 to the remaining terminals of the solenoids. Theother output terminal of the receiver is connected by conductor 34 tobattery 35, the other side of the battery is extended to rotary arm 30by line 36 including switch 31.

On reception of an impulse at the receiver 23, the receiving circuit isenergized instantaneously and includes conductor 34, battery 35,conductor 36, switch 31, rotary arm 30, any contact 29 and theparticular conductor 32 and solenoid 26 corresponding to the contact 29engaged by arm 30, and conductor 33 back to receiver 23. Upon completionof said circuit the particular said solenoid is energized causing thecharacter correspondingto the contact 29 to be printed on the roll 2.The characters printed will appear in the same order in which they aresent inasmuch as the said arms 1 and 30 are always in like relationshipto the contacts engaged thereby due to their synchronous rotation.

In order to bring the sending rotary arm 1 into register with receivingarm 36, with respect to the contacts of distributors 5 and 28, thesending operator rst transmits a predetermined signal for a giveninterval, whereupon the receiving operator sets the arm 30 on a givencontact 29 corresponding to the predetermined position of the arm 1 onthe sending distributor.

It will be evident that the switch I4 being open at the receiving endrenders the condensers II inoperative and ineffective, and in likemanner the receiving switch 31 being open at the sending end, rendersthe receiving circuit inoperative. Thus the vapparatus installed at anystation may be used interchangeably for sending or receiving on properadjustment of the said switches.

While there has been shown and described and pointed out the fundamentalnovel features of the invention as applied to a single modification, itwill be understood that various omissions and substitutions and changesin the form and details of the device illustrated and in its operationmay be made by those skilled in the art without departing from thespirit of the invention. It is the intention therefore to be limitedonly as indicated by the scope of the following claims.

What is claimed is as follows:

l. In a communication system, capacitive reactance devices correspondingto characters to be transmitted, means to supply current to saiddevices, means for initiating transmission of signals corresponding tosaid characters, and means to effect transmission of initiated charactersignals upon supplying current to said devices.

2. In a communication system, means for initiating transmission ofcharacter signals, a plurality of charge accumulating devicescorresponding to characters to be transmitted, means under control ofinitiating means for charging said devices, and means to transmitinitiated character signals upon charging of said devices.

3. In a communication system, a plurality of elements for initiatingcharacter signals, means cooperating with said elements to supply energyfor transmission of character signals, means under control of saidinitiating means for energizing rst named means, and means for effectingenergization of rst named means to cause transmission of initiatedcharacter signals upon energization of rst named moans.

4. In a communication system, a plurality of condensers, onecorresponding to each character to be transmitted, means for chargingsaid condenser, a mechanism for initiating transmission of signalscorresponding to the diierent characters and means under control ofinitiating means for effecting charging of the diierent condensers atdifferential times in accordance with the different characters to betransmitted.

5. A signal controlling circuit having a source of current supply, anelement for initiating ow of current from said supply through thecircuit, a condenser in the circuit charged by the iiow of current uponoperation of said initiating element to vary the circuitcharacteristics, and means controlled by the circuit by and uponvariation of the current characteristics to transmit a signal.

6. In a communication system, a sending malchine having chargeaccumulating devices,

activated upon energization of the corresponding reactance elements.

8. In a communicationv system, a sending machine having capacitivereactance elements, key bars, each associated with a reactance element,circuits operated by the correspondingkey bars for energizing saidelements upon operation of the key bars, a transmission circuitconnected to the rst named circuits, and means associated with the iirstnamed circuits to activate said transmission circuit upon energizationof the corresponding reactance elements.

9. In a communication system, a sending machine having capacitivereactance elements, key bars, eachv associated with a reactance element,circuits operated by the corresponding key bars for energizing saidelements upon operation of the key bars, a transmission circuitconnected to the rst named circuit, and electrical impeding meansassociated with the rst named 'circuits to activate said transmissioncircuit upon energization of the reactance elements.

10. Ina communication system, a sending machine having key hars,` acondenser for each. bar, contact members corresponding to said bars andconnected respectively to said condensers to receive the chargingcurrent for said condensers respectively upon operation of said bars,and a transmission circuit to be energized by the flow of chargingcurrent through said contacts to said condensers.

11. I n a communication system, a sending machine having key bars,condensers for each keybar, circuits for charging said condensers, thekey bars operable for initiatng operation of its corresponding circuit,contact members corresponding to said bars and connected respectively tosaid condensers to receive charging current for said condensers, atransmission circuit connected to the iirst named circuits to beenergized by said condenser charging current, and means associated withsaid contact members to complete the operation of the rst named circuitsto charge the condensers and to cause the energization of saidtransmission circuit.

12. In a communication system, a sending machine having capacitivereactance elements, depressible key bars, circuits for energizing saidelements upon return movement of the key bars. and a transmissioncircuit connected to the rst named circuits and activated uponenergization of the reactance elements.

13. In a communication system, a sending machine having capacitivereactance elements, depressible key bars, each associated with areactance element, circuits operated by the corresponding key bars forenergizing said elements upon return movement of the key bars, atransmission circuit connected to the rst named circuits, and meansassociated with the first named circuits to activate said transmissioncircuit upon energization of the corresponding reactance elements.

14. In a communication system, a sending machine having key bars, acondenser for each key bar, circuits operated by the corresponding keybars for charging said condensers upon return movement of the key bars,a transmission circuit connected to the rst named circuits, and a commonresistor connected to the rst named cir` cuits to energize saidtransmission circuit upon the charging of the condensers.

15. In a communication system, a sending machine having key bars, acondenser for each key bar, circuits operable by the key bars forcharging its corresponding condenser upon return movement of the keybars, a resistor connected to said circuits, a transmission circuitconnected to the rst named circuits to be energized upon flow of thevcharging current through the resistor, a receiving circuit sensitive tothe transmission circuit, printing members associated with said keybars, electrical devices in said receiving circuit for operating saidkey bars and printing members, and a selecting switch for renderingeither said receiving circuit or said condensers, inoperative andrendering the other operative.

16. In a communicating system, a 'printing man chine having key bars, acondenser for each key bar, circuits operable by the key bars forcharging its corresponding condenser upon return movement of the keybars, a resistor connected to said circuits, a transmission circuitconnected to the first named circuits to be energized upon ow of thecharging current through the resistor a receiving circuit, printingmembers associated with said key bars, electrical devices in saidreceiving circuit for selectively operating said key bars and printingmembers, and a selecting' switch for permanently rendering either saidreceiving circuit or said condenser circuit inoperative and renderingthe other operative.

WALTER s. LEMMON. cnYDE J. FITCH.

